Set name attribute of radio-groups which are scoped to the instance

[cravindra]

Decouples the name attribute from the model value and makes it unique
across multiple instances of radio fields which may now share the same
model value and still operate independently

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  Bug fix

• What is the current behavior? (You can also link to an open issue here)
  Having multiple components with radio buttons makes it so that only one of them is visibly selected at a time #695

• What is the new behavior (if this is a feature change)?
  Radio fields now generate a unique name which is shared within an instance and unique across different instances

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  No

• Other information:

[coveralls]

Coverage remained the same at 89.979% when pulling ee5abf3 on cravindra:scoped-radio-groups into 721a4ee on vue-generators:master.